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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "ufdt_prop_dict.h"
#include "libfdt.h"
#include "libufdt_sysdeps.h"
#define UFDT_PROP_DICT_INIT_SZ 4
/* Empirical values for hash functions. */
#define HASH_BASE 13131
#define DICT_LIMIT_NUM 2
#define DICT_LIMIT_DEN 3
static int _ufdt_prop_dict_str_hash(const char *str) {
int res = 0;
for (; *str != '\0'; str++) {
res *= HASH_BASE;
res += *str;
}
return res;
}
static const struct fdt_property **_ufdt_prop_dict_find_index_by_name(
const struct ufdt_prop_dict *dict, const char *name) {
/* size should be 2^k for some k */
int hash = _ufdt_prop_dict_str_hash(name);
int size = dict->mem_size;
int idx = hash & (size - 1);
/* If collision, use linear probing to find idx in the hash table */
for (int i = 0; i < size; i++) {
const struct fdt_property **prop_ptr = &dict->props[idx];
const struct fdt_property *prop = *prop_ptr;
if (prop == NULL) return prop_ptr;
const char *prop_name = fdt_string(dict->fdtp, fdt32_to_cpu(prop->nameoff));
if (dto_strcmp(prop_name, name) == 0) return prop_ptr;
idx = (idx + 1) & (size - 1);
}
return NULL;
}
static const struct fdt_property **_ufdt_prop_dict_find_index(
struct ufdt_prop_dict *dict, const struct fdt_property *prop) {
const char *name = fdt_string(dict->fdtp, fdt32_to_cpu(prop->nameoff));
return _ufdt_prop_dict_find_index_by_name(dict, name);
}
int _ufdt_prop_dict_construct_int(struct ufdt_prop_dict *dict, void *fdtp,
int size) {
const size_t entry_size = sizeof(const struct fdt_property *);
const struct fdt_property **props =
(const struct fdt_property **)dto_malloc(size * entry_size);
if (props == NULL) return -1;
dto_memset(props, 0, size * entry_size);
dict->mem_size = size;
dict->num_used = 0;
dict->fdtp = fdtp;
dict->props = props;
return 0;
}
int ufdt_prop_dict_construct(struct ufdt_prop_dict *dict, void *fdtp) {
return _ufdt_prop_dict_construct_int(dict, fdtp, UFDT_PROP_DICT_INIT_SZ);
}
void ufdt_prop_dict_destruct(struct ufdt_prop_dict *dict) {
if (dict == NULL) return;
dto_free(dict->props);
}
static int _ufdt_prop_dict_enlarge_if_needed(struct ufdt_prop_dict *dict) {
if (dict == NULL) return -1;
/* Enlarge if the used number over than DICT_LIMIT_NUM / DICT_LIMIT_DEN */
if (dict->num_used * DICT_LIMIT_DEN <= dict->mem_size * DICT_LIMIT_NUM) {
return 0;
}
int new_size = dict->mem_size * 2;
struct ufdt_prop_dict temp_dict;
_ufdt_prop_dict_construct_int(&temp_dict, dict->fdtp, new_size);
for (int i = 0; i < dict->mem_size; i++) {
const struct fdt_property *prop = dict->props[i];
if (prop == NULL) continue;
const struct fdt_property **new_prop_ptr =
_ufdt_prop_dict_find_index(&temp_dict, prop);
if (new_prop_ptr == NULL) {
dto_error("ufdt_prop_dict: failed to find new index when enlarging.\n");
ufdt_prop_dict_destruct(&temp_dict);
return -1;
}
*new_prop_ptr = prop;
}
dto_free(dict->props);
dict->mem_size = new_size;
dict->props = temp_dict.props;
return 0;
}
int ufdt_prop_dict_add(struct ufdt_prop_dict *dict,
const struct fdt_property *prop) {
const struct fdt_property **prop_ptr = _ufdt_prop_dict_find_index(dict, prop);
if (prop_ptr == NULL) {
dto_error("ufdt_prop_dict: failed to find new index when adding.\n");
return -1;
}
if (*prop_ptr == NULL) dict->num_used++;
*prop_ptr = prop;
return _ufdt_prop_dict_enlarge_if_needed(dict);
}
const struct fdt_property *ufdt_prop_dict_find(const struct ufdt_prop_dict *dict,
const char *name) {
const struct fdt_property **prop_ptr =
_ufdt_prop_dict_find_index_by_name(dict, name);
return prop_ptr ? *prop_ptr : NULL;
}
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